The invention relates to tufting brushes.
Toothbrushes generally include a body having a handle portion, a head portion, and bristles extending from the head portion. The bristles can be arranged in the form of a number of tufts.
Toothbrushes are manufactured by injecting liquid plastic into a mold cavity that defines a toothbrush body. Tufts of bristles are then attached to the head portion of the toothbrush body in a process generally known as tufting. Tufting of toothbrushes can be done by stapling, hot tufting, welding or molding tufts of bristles into the toothbrush body.
The invention relates to a composite mold in which tufts of bristles can be inserted and maintained in a predetermined position while being subjected to an injection molding operation to form a brush. The composite mold includes a mold cavity defining a portion of an oral brush head.
In one aspect, the invention features a composite brush mold that includes a) a metallic component that includes a pattern of holes extending from a first surface of the metallic component to a second surface of the metallic component, in which the holes are configured to receive tufts that include at least one bristle, and b) a second component that includes a pattern of fingers that correspond to the pattern of holes, where the fingers extend into the holes to form end walls. Preferably the second component is plastic.
By using a composite mold, bristles may extend at a variety of angles to the surface of the brush head. The bristles can also extend to a variety of heights from the brush head. The ability to vary the topography of the second component while maintaining the same two-dimensional pattern at the base of the second component allows the use of multiple second components with a single metallic component.
Particular advantages exist when the second component is plastic. For example, the plastic component of the composite mold is inexpensive to manufacture and modify relative to the costs associated with manufacturing and modifying the topography in metallic molds, thus providing design flexibility. In addition, because the plastic component can be produced from a mold, the dimensions of the plastic component can be produced with excellent precision and accuracy. The plastic component also can be replaced when it wears out or is no longer working, and the metallic component, which may have a longer useful life, can be reused.
The properties of the plastic component enable the plastic component to maintain a sufficiently tight relationship with the metallic component when the two components are mated, while allowing the easy separation of the two components when disassembly is desired. The ability to disassemble the composite mold enables the mold and the holes therein to be easily cleaned.
In one embodiment, the metallic component further includes a cavity located at the first surface of the metallic component such that the holes extend from the cavity, and the cavity defines a portion of an oral brush from which tufts of bristles extend. In some embodiments, the mold further includes a plurality of cavities located at the first surface of the metallic component such that the pattern of holes extends from the cavities to the second surface.
In other embodiments, the pattern of holes includes a first plurality of holes and a second plurality of holes. The plastic second component can further include a first component that includes a plurality of fingers dimensioned to be inserted into the first plurality of holes, and a second component that includes a plurality of fingers dimensioned to be inserted into the second plurality of holes.
In another embodiment, the first plurality of holes extend at a first angle to the first surface, and the second plurality of holes extend at a second angle to the first surface, the second angle being different from the first angle.
In some embodiments, the first plurality of holes have a first cross-section, and the second plurality of holes have a second cross-section, where the first cross-section is different from the second cross-section.
In preferred embodiments, the composite mold is dimensioned to be inserted into an apparatus for manufacturing oral brushes. The mold can further include a plurality of the metallic components, a plurality of the second components, or a combination thereof.
In another aspect, the invention features a method for forming a brush where the method includes contacting a first end of a tuft of bristles extending from a hole in the above-described composite mold with molding compound to form a brush.
Other features of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.